The present invention relates to a dust cover.
As shown in FIG. 1, a prior art dust cover 10 is formed of a plurality of shield plates similar in shape and different in size such that they are progressively smaller. The shield plates are joined together such that they are moved one after another, with the first shield plate acting like a locomotive. The dust cover can be thus expanded or retracted.
The prior art dust cover has several shortcomings. In the first place, the prior art dust cover is noisy in view of the fact that the shield plates collide with one another to make noise at the time when they are pulled one after another. In order to avert the noise, the shield plates are provided with a plastic silencer., which is vulnerable to damage caused by the engine oil, the rustproof machining fluid, the collision, etc. The damaged plastic silencer must be replaced every three months. In light of the pulling of the shield plates one after another, the dust covers are apt to be unparalleled. As a result, the dust covers are eventually moved in a curved path, thereby resulting in damage of the dust covers.
The primary objective of the present invention is to provide a dust cover which is quiet and capable of moving simultaneously in a parallel manner.
The dust cover of the present invention comprises a plurality of shield plates which are equal in shape to one another, and different in size such that the size is progressively reduced. The shield plates are joined together to expand or retract axially. The dust cover further comprises a linking device which is formed of a plurality of link rod units, with each having two rod members equal in length. The two rod members are pivoted together at the midpoints thereof such that two ends of the two rod members form a pair of arms capable of opening and closing. The two arms of each side of each link rod are pivoted with the two arms of other link rod to form two pivoting points, which are pivoted under the same shield plate, thereby forming an expandable and retractable device for linking the dust cover.